In the construction industry, there is always a premium on enabling the installer to use electrical outlet boxes which can be easily connected to each other laterally (ganged) and/or positioned on a wall or ceiling joists at a desired "depth". The depth depends on the thickness of the wallboard to be attached to the stud or joist. Additionally, it is beneficial to have boxes which tend to be universal in that they can be attached to commercial attachment plates or to new plates designed specifically for use with the newer boxes.
There have been a number of approaches to solving these problems. Examples of these approaches include those of the following references:
A Carlon brand box manufactured by the Lamson-Sessions Company of Cleveland, Ohio, U.S.A. with the patent marking of U.S. Pat. No. 3,895,732 to R. L. Robinson et al uses an "L" shaped metal flange attached to the side of a plastic electrical box. Each of the box sides have opposed "L" shaped flanges which are closed toward the open end of the box. Centered between the lower end of the flanges is an angled ramp. The edges of the base of a metal flange are slipped under the "L" shaped projections and the flange is pushed up and over the vertical side of the angled ramp to lock the flange in place. The other leg of the flange has, in one form, rear facing pointed projections which are driven into the face of a support prior to driving nails or screws through holes in the leg and into the support.
A second commercial Carlon PVC switch box marked with U.S. Pat. No. 4,304,958 to S. W. Ness et al, has a flange on each end perpendicular to the surface of the open end of the box. On two tangentially opposed corners, there are recesses through which screws, extending about half the depth of the box position, and by turning the screws, move clamps which are screwed onto their pointed ends. The clamps have holes at the base for insertion of the screws. The clamps rotate so as to be positioned behind the flanges during insertion into a hole in a wall and perpendicular to the end surfaces during use as a clamp.
In still another commercial design manufactured by Veco Products, Inc. of Lyle, Washington, U.S.A. and based on U.S. Pat. No. 5,289,934 to B. H. Smith et al, a plastic electrical box has front to back grooves in the top and bottom of the box adjacent the edges on one side. An attachment bracket has two recurved edges which fit into the grooves and serve to align the bracket parallel to the box. The bracket has perforated "wings" which extend beyond the top and bottom edges of the box. It also has an "L" extension which is positioned perpendicular to the box. The lower leg of the "L" has teeth at the edge of the bottom leg which are parallel to the larger leg of the "L". The shorter leg of the "L" is forced (hooked) over a stud, the teeth driven into the side of the stud, the box forced against the other side of the stud, and nails are driven through the winged perforations to affix the box to the stud. The front of the box can be extended from or retracted into the wall by turning a screw mechanism rotatable anchored in the side of the box to which the piece is attached.
Several other approaches have been taken to the solution of receptacle attachment and positioning problems. Some of these are discussed in exemplary patents below.
U.S. Pat. No. 4,062,470 to W. C. Bateler describes an outlet box with an "L" shaped mounting bracket and an electrical box with a pair of slots formed by bases which receive and seat the slotted side of the bracket. As the slotted bracket side enters the slots, it rides up over a wedge until seated. At this point, the wedge has fitted into the slot and prevents the bracket from separating from the box.
U.S. Pat. No. 4,408,696 to W. J. Crosson teaches an electrical box with a flanged front and clamps mounted with their bases in channels in the wall of the box. Screws projecting through the flange and the clamps are used to pull the clamp toward the rear surface of the wall and clamp the box onto wallboard.
U.S. Pat. No. 4,612,412 issued to J. J. Johnson describes utility boxes attached to each other and to a bracket by rails and channel members which interlock at several predetermined positions. For attachment to a stud, a bracket is used. The bracket has a center section which projects outwardly from the two end sections. Rail segments are positioned on each end of the central projection parallel to the end sections. A centered line of inwardly tapered parallel recesses divides the central projection. At the ends of one side of the box "C" channels extend from the edges and form a channel. The end edges of the other side of the box have rails which slip into the "C" channels. Centered between the "C" channels is a retainer lug which slips into a chosen parallel recess in the centered line of parallel recesses in the bracket or an central aperture in the opposite wall of the box to provide a desired attachment depth. A second interlocking clamp arrangement fixes cables at desired positions in the box.